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added 'pure' function attribute - fixed indirect function calls

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git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4469 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
bellard 2008-05-17 12:42:15 +00:00
parent 0b6ce4cffe
commit c6e113f568
2 changed files with 46 additions and 23 deletions
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63
tcg/tcg.c
View File

@ -946,32 +946,51 @@ void tcg_liveness_analysis(TCGContext *s)
def = &tcg_op_defs[op];
switch(op) {
case INDEX_op_call:
nb_args = args[-1];
args -= nb_args;
nb_iargs = args[0] & 0xffff;
nb_oargs = args[0] >> 16;
args++;
{
int call_flags;
/* output args are dead */
for(i = 0; i < nb_oargs; i++) {
arg = args[i];
dead_temps[arg] = 1;
}
nb_args = args[-1];
args -= nb_args;
nb_iargs = args[0] & 0xffff;
nb_oargs = args[0] >> 16;
args++;
call_flags = args[nb_oargs + nb_iargs];
/* globals are live (they may be used by the call) */
memset(dead_temps, 0, s->nb_globals);
/* pure functions can be removed if their result is not
used */
if (call_flags & TCG_CALL_PURE) {
for(i = 0; i < nb_oargs; i++) {
arg = args[i];
if (!dead_temps[arg])
goto do_not_remove_call;
}
tcg_set_nop(s, gen_opc_buf + op_index,
args - 1, nb_args);
} else {
do_not_remove_call:
/* input args are live */
dead_iargs = 0;
for(i = 0; i < nb_iargs; i++) {
arg = args[i + nb_oargs];
if (dead_temps[arg]) {
dead_iargs |= (1 << i);
/* output args are dead */
for(i = 0; i < nb_oargs; i++) {
arg = args[i];
dead_temps[arg] = 1;
}
/* globals are live (they may be used by the call) */
memset(dead_temps, 0, s->nb_globals);
/* input args are live */
dead_iargs = 0;
for(i = 0; i < nb_iargs; i++) {
arg = args[i + nb_oargs];
if (dead_temps[arg]) {
dead_iargs |= (1 << i);
}
dead_temps[arg] = 0;
}
s->op_dead_iargs[op_index] = dead_iargs;
}
dead_temps[arg] = 0;
args--;
}
s->op_dead_iargs[op_index] = dead_iargs;
args--;
break;
case INDEX_op_set_label:
args--;
@ -1640,7 +1659,7 @@ static int tcg_reg_alloc_call(TCGContext *s, const TCGOpDef *def,
}
/* mark dead temporaries and free the associated registers */
for(i = 0; i < nb_params; i++) {
for(i = 0; i < nb_iargs; i++) {
arg = args[nb_oargs + i];
if (IS_DEAD_IARG(i)) {
ts = &s->temps[arg];

4
tcg/tcg.h
View File

@ -148,6 +148,10 @@ typedef int TCGv;
#define TCG_CALL_TYPE_REGPARM_1 0x0001 /* i386 style regparm call (1 reg) */
#define TCG_CALL_TYPE_REGPARM_2 0x0002 /* i386 style regparm call (2 regs) */
#define TCG_CALL_TYPE_REGPARM 0x0003 /* i386 style regparm call (3 regs) */
/* A pure function only reads its arguments and globals variables and
cannot raise exceptions. Hence a call to a pure function can be
safely suppressed if the return value is not used. */
#define TCG_CALL_PURE 0x0010
typedef enum {
TCG_COND_EQ,